The present invention relates to the field of three dimensional imaging in general, the field of three dimensional (3D) video imaging in particular and specifically to three dimensional imaging systems for dentistry.
The use of video cameras in dentistry is a well known in the prior art. Different types of video cameras are used by dentists for viewing the oral cavity, magnifying the view thereof and for recording video images of the oral cavity or selected parts thereof.
Dentists routinely use an inter-oral camera (IOC) inserted into the patients mouth for inter-oral photography. An IOC is usually used in teeth implantation for obtaining exact video photographs used for the precise measurements and three dimensional reconstruction needed for preparing the rehabilitation infrastructure.
Unfortunately, inter-oral cameras need to be sterilized before each use. The camera and the handpiece cannot be sterilized, thus forcing the use of impeding sterilizable plastic enclosures, an expensive and time consuming procedure.
Additionally, inter-oral cameras lack zooming capacity due to the limited possible size of the lens. Some IOC""s have a limited capacity for up to three different magnification levels but no continuous zooming capacity. Furthermore, the large size of the handpiece and the power-cord of inter-oral cameras is obstructive to the practitioner performing dental work.
U.S. Pat. No. 4,395,731 to Schoolman discloses the combination of a pair of video cameras and video screens, mounted on a users head to provide a microscope for surgeons. In this arrangement, however, the surgeon does not see the real world, but sees only the image displayed on the video screens directly in front of his eyes.
U.S. Pat. No. 4,516,157 to Campbell discloses a portable electronic camera. This invention teaches an electronic video device including a pair of spectacles adapted to be worn on a user""s head and having the object of providing a readily portable electronic video means for recording video images in which the video image substantially corresponds to the view directly seen by the operator wearing the device.
Dentists practicing the fitting of fixed prostheses supported by osseo-integrated implants routinely perform photogrammetric measurements of implant positions. Such measurements require the use of specially adapted cameras for taking still photographs of the implants followed by photogrammetric measurements of the developed film. This method requires precision manual photogrammetric measurement and calibration techniques which are time consuming, expensive and which requires considerable expertise. Additionally, prior art of photogrammetric measurement of implant positions requires developing the film before measurements can be performed, adding to the cost and duration of the procedure.
It will be appreciated by those skilled in the art that although the 3D video viewing system disclosed hereinbelow in accordance with the preferred embodiments of the present invention is adapted for use by dentists, certain aspects of the invention are equally applicable to other types of use. The system can also be generally adapted for use in any application where a system is needed to enable a person to view objects two-dimensionally or three-dimensionally on a video display, with or without zooming capability, while having both hands free to manipulate the objects and while retaining the possibility of direct visual control of the objects. For example the system can be used for inspection and repair of electronic circuit boards, for assembling or taking apart of multi-component mechanical devices such as watches or any other mechanical devices or for surgery.
One object of the present invention is to provide a video system for providing a dentist with a three-dimensional or two-dimensional video image of the oral cavity of a patient.
A feature of a preferred embodiment of the present invention is the use of a video system placed outside of the oral cavity of the patient, thus allowing the dentist unobstructed access to the oral cavity.
A feature of another preferred embodiment of the present invention is the use of a zooming video system for providing a user controlled, variable magnification of the image of the oral cavity.
Another object of the present invention is to provide a video system for producing a composite video image composed of three different superimposed video images, each of the three video images taken from a different angle of view. The composite video image can be fed to a host computer for performing various photogrammetric measurements thereon, thus obviating the use of a photogrammetric still camera and the processing of the film.
A feature of a preferred embodiment of the present invention is that the video system which is used for providing a three dimensional video image of the oral cavity, can also be used for providing a composite video image for photogrammetric measurements, thus obviating the need for a separate photogrammetric camera.
There is therefore provided, in accordance with a preferred embodiment of the present invention, a video system for providing an operator with a three dimensional stereoscopic image of the oral cavity of a patient. The system includes an imaging unit for providing at least two stereoscopic images of the oral cavity, a pair of switchable shutters for alternatingly blocking the view of the left eye and the right eye of the operator, a synchronizing unit for synchronizing the switching of the pair of switchable shutters with the rate of generation of the two stereoscopic video images by the imaging unit and a video display for displaying the two stereoscopic images.
Further, in accordance with another preferred embodiment of the present invention, the imaging unit of the video system includes a video camera and an optical assembly disposed between the video camera and the oral cavity for alternatingly providing the video camera with at least two different stereoscopic images of the oral cavity in synchrony with the field rate of the video camera.
Further, in accordance with yet another preferred embodiment of the present invention, the optical assembly is also operative to simultaneously provide a first image of the oral cavity along a first optical axis of the optical assembly, and a pair of second and third stereoscopic images of the oral cavity along a second and third optical axes of the optical assembly, respectively. The second and third optical axes are inclined at an angle to the first optical axis, and the three different images are superimposed upon the imager of the video camera to provide a composite video image.
Additionally, in accordance with yet another preferred embodiment of the present invention, the synchronizing unit also digitizes the composite video image and provides a host computer with a digitized composite video image for performing photogrammetric measurements thereon.
Furthermore, in accordance with still another preferred embodiment of the present invention, the imaging unit comprises two video cameras providing a pair of stereoscopic images of the oral cavity and the synchronizing unit synchronizes the two video cameras with the switching rate of the switchable shutters.
Furthermore, in accordance with another preferred embodiment of the present invention, the imaging unit also includes two folding mirrors for folding the light reflected from the oral cavity towards the two video cameras.
Furthermore, in accordance with yet another preferred embodiment of the present invention, the imaging unit is attached to a harness worn on the head of the operator.
Furthermore, in accordance with still another preferred embodiment of the present invention, the video system also includes a folding mirror for folding the light reflected from the oral cavity towards the imaging unit.
Further yet, in accordance with another preferred embodiment of the present invention, the synchronizing unit provides multiplexed left and right video image signals to the video display at a rate which is double the field rate of the video camera for providing the operator with a flicker-free image of the oral cavity on the video display.
Furthermore, in accordance with yet another preferred embodiment of the present invention, the switchable shutters are liquid-crystal shutters.
Further yet, in accordance with still another preferred embodiment of the present invention, the video camera further comprises a zoom lens controllable by the operator for providing the three dimensional stereoscopic images and the composite video image at a selectable magnification.
There is also provided, in accordance with still another preferred embodiment of the present invention, a video system for providing an operator with a two-dimensional video image of the oral cavity of a patient. The video system includes a harness wearable on the head of the operator, a video camera attached to the harness for imaging the oral cavity and a video display connected to the video camera for displaying the video image.
Further yet, in accordance with still another preferred embodiment of the present invention, the video camera further comprises a zoom lens controllable by the operator for providing the two-dimensional stereoscopic images at a selectable magnification.
Finally, in accordance with still another preferred embodiment of the present invention, the two-dimensional video system further includes a folding mirror for directing the light from the oral cavity to the video camera.